Elastomeric conductor and shield fault detection

ABSTRACT

Systems and methods are provided for early detection of wire/cable faults. For example, a system may detect electrical/electronic faults with power lines, data lines, communication lines, coaxial cables, and the like (generally referred to herein as “lines”, “wires”, and “cables”) by providing sacrificial materials including a conductive material external to the lines. A processor may be coupled to the conductive material to transmit a control signal along the conductive material of the line to determine whether the line is degrading. That is, when the sacrificial material wears away and exposes the conductive sacrificial material in the line, that conductive material may begin to experience faults. The faults in the external conductive material may serve as precursors to the overall degradation of the line. Thus, the line may be repaired or replaced prior to the degradation of the line itself.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation patent application claimingpriority to and thus the benefit of an earlier filing date from U.S.patent application Ser. No. 12/351,613 (filed Jan. 9, 2009), andpatented as U.S. Pat. No. 8,099,254, which claims priority to and thusthe benefit of an earlier filing date from U.S. Provisional PatentApplication No. 61/020,623 (filed Jan. 11, 2008), the entire contents ofeach of which are incorporated by reference.

BACKGROUND

Electrical wiring is used to conduct electrical current in a variety ofapplications. For example, electrical wiring is used to conductelectrical energy for the purposes of power delivery. Electrical wiringis also used in data transmissions between electronics devices.Exceptionally important applications include the various power and datadelivery uses in human related services, such as transportation (e.g.,plane, automobile, etc.) and medical care.

Over time, wiring can deteriorate due to environmental conditions andultimately degrade wire integrity. For example, excessive flex, chafingbetween adjacent wires, lack of strain relief, altitude, temperature,humidity, and/or acceleration can jeopardize the integrity of the wire.When a wire breaks, open circuit conditions are created that contributeto a loss of signal integrity, component failures, or even catastrophicfires. Due to the intermittent nature of most of cable failures, theseproblems are often difficult to detect and more difficult to repair.

Hard faults (i.e., those fault where a wire has completely failed) arequickly detected using common circuit testing equipment. Intermittentfaults, however, are much more difficult to detect because the faultsare generally only detectable when the wire is live (e.g., operational).Time domain reflectometry can detect intermittent events in live wiresby monitoring the wire over a period of time. For example, a time domainreflectometer (TDR) may transmit a relatively short rise time pulsealong a conductor. If the conductor is of a uniform impedance andproperly terminated, the entire transmitted pulse is absorbed in thefar-end termination. Thus, no signal is reflected towards the timedomain reflectometer. Impedance discontinuities in the wire, however,cause a portion of the incident signal to be reflected back towards thesource. The intermittent fault and even the location of the fault may bedetermined from the reflected signal. Accordingly, if the faulty wire ismonitored over some period of time with the time domain reflectometer, afault in the wire is likely to be detected by the time domainreflectometer.

Detection of wire faults is possible after the fault occurs. However,detection after the fact may be too late. For example, an aircraft withaging deteriorating wires may begin to experience intermittent faults inthe wiring. TDR testing of the wires may be performed as part ofmaintenance on the aircraft while the aircraft is not in-flight torepair/replace faulty wires. But, intermittent faults are likely tooccur while the aircraft is in flight, jeopardizing the safety of thepeople on board.

SUMMARY

The systems and methods described herein provide for the early detectionof wire/cable faults. For example, the systems and methods describedherein may detect electrical/electronic faults with power lines, datalines, communication lines, coaxial cables, and the like (generallyreferred to herein as “lines”, “wires”, and “cables”) by providing asacrificial materials including a conductive material external to thelines. A processor may be coupled to the conductive material to transmita control signal along the conductive material of the line to determinewhether the line is degrading. That is, when the sacrificial materialwears away and exposes the conductive sacrificial material in the line,that conductive material may begin to experience faults. The faults inthe external conductive material may serve as precursors to the overalldegradation of the line. Thus, the line may be repaired or replacedprior to the degradation of the line itself.

In one embodiment, a system for determining line integrity includes aninsulated line that includes a conductive material surrounding theinsulation of the insulated line. The insulated line further includes asacrificial material surrounding the conductive material. The insulatedline also includes a processor (e.g., a time domain reflectometer)operable to communicatively couple to the conductive material todetermine integrity of the insulated line.

The sacrificial material may be configured from Teflon or anothersuitable material. The conductive material may be configured from ametallic ink, a nanoparticulate material (e.g., carbon nanotubes). Theprocessor may be configured to determine degradation of the sacrificialmaterial via the conductive material. The insulated line may include anelastic primary configured from a nano particulate material. Theconductive material may have a thickness less than about 100 nm.

In another embodiment, a method of determining line integrity mayinclude providing an insulated line. The insulated line includes aconductive material surrounding the insulation of the insulated line anda sacrificial material surrounding the conductive material. The methodmay also include coupling to the conductive material of the insulatedline, transmitting a control signal along the conductive material, andmeasuring an electrical characteristic of the control signal todetermine the line integrity. For example, measuring the electricalcharacteristic includes determining voltage changes in the controlsignal from a point where the control signal is transmitted to theconductive material. The method further including determining integrityof the sacrificial layer based on the electrical characteristic of thecontrol signal. Coupling to the conductive material may include couplinga time domain reflectometer to the conductive material.

In another embodiment, a system for determining line integrity includesa coaxial cable that includes a primary, a dielectric material, ashielding, and an insulator. The coaxial cable further includes aconductive material surrounding the insulator and a sacrificial materialsurrounding the conductive material. The system also includes aprocessor operable to communicatively couple to the conductive materialto determine integrity of the insulated line.

BRIEF DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element or same type ofelement on all drawings.

FIG. 1 is a system that provides for the early detection of line faults.

FIG. 2 is a system that provides for the early detection of coaxialcable faults.

FIG. 3 illustrates a connector employing a TDR module for detectingwire/cable faults.

FIG. 4 is a flowchart of a process for detecting line faults.

DETAILED DESCRIPTION OF THE DRAWINGS

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that it is not intended to limit the inventionto the particular form disclosed, but rather, the invention is to coverall modifications, equivalents, and alternatives falling within thescope and spirit of the invention as recited in the claims.

FIG. 1 is a perspective cut away view of a system 10 that provides forthe early detection of line faults. The system 10 includes a processor11 and a line 16. The line 16 may be configured in a variety of waysbased on the particular need of the line 16. For example, the line 16may be an insulated wire for use in a twisted-pair configuration, acoaxial cable for use in communications, an elastic wire/cable, etc. Inthis regard, the line 16 may be configured with a conductive primary 15and an insulator 14. Differing from previous configurations, the line 16includes a conductive material 13 surrounding the insulator 14 and aninsulating sacrificial material 12 surrounding the conductive material13. For example, the conductive material 13 may be configured from anano particulate material that is conductive, such as that disclosed incommonly owned and co pending U.S. patent application Ser. No.12/351,463 (filed Jan. 9, 2009; the “'463 application”), the entirecontents of which are incorporated within by reference. Alternatively,the conductor 13 may be configured of traditional metal wire. Thisconductive material 13 may be substantially thin (e.g., less than about100 nm) so as to not add significantly to the overall weight of the line16. The conductive material 13 may be used to detect faults in the line16 prior to the faults affecting the conductive primary 15.

The sacrificial material 12 may also be configured from relativelylightweight materials, such as Teflon tape, that provides someprotection for the conductive material 13. For example, degradation of awire over time generally occurs due to conditions that are external tothe line 16. In other words, chafing, environmental conditions,chemicals, and the like, tend to wear away the wire from the outside in.Eventually, these conditions affect the integrity of the conductivematerial within the wire and ultimately create faults within the wire.To detect these faults prior to failure, the line 16 is surrounded bythe conductive material 13 and the sacrificial material 12. Thedegradation of the line 16 may therefore be detected by the processor 11before the primary 15 is affected.

In one embodiment, conductive material 13 may be configured from ametallic “ink” such as that produced by Cima Nanotech, Inc., of St.Paul, Minn. In such an embodiment, the metallic ink may be coated on theinsulating material 14 like a paint. The sacrificial material 12 maythen be wrapped about the metallic ink to provide a certain level ofprotection. After some period of time, the sacrificial material 12 maybegin to experience the same effects of degradation common totraditional lines. For example, chafing, environmental conditions,chemicals, etc., that over time degrade traditional lines, may have thesame effect of wearing away the sacrificial material 12 and exposing theconductive material 13. Once exposed, the conductive material 13 mayexperience similar failures seen in degrading wires. Thus, the detectionof these faults within the conductive material 13 may serve as aprecursor to the degradation of the overall line 16. In other words,detection of the faults within the conductive material 13 may be used toidentify when and where faults may occur within the primary 15 prior tothem actually happening.

As is commonly the case with traditional line integrity detection,detection of the degradation in the line 16 generally occurs after thefact. For example, the processor 11 may be a time domain reflectometerthat is used to test the integrity of the line 16 after the line hasbeen in use. The processor 11 may be coupled to the conductive material13 to propagate a pulse down the line 16 and, when the far end of theline 16 is shorted (i.e., terminated into zero ohms impedance), thevoltage at the launching point of the pulse steps up to a given valueinstantly and the pulse begins propagating down the line 16 towards theshort. When the pulse hits the short, the energy is not absorbed at thefar end of the line 16. Rather, the pulse reflects from the shorttowards the launching end. When the opposing reflection finally reachesthe launch point, the voltage at the launching point abruptly drops tozero signaling that there is a short at the end of the line 16. In otherwords, the TDR has no indication that a short exists until the pulsetravels along the line 16 at roughly the speed of light and echoes backat the same speed. Assuming the signal propagation speed in the line 16is known, the distance to the short can then be measured.

A similar effect occurs if the far end of the line 16 is an open circuit(i.e., terminated into an infinite impedance). In this case, thereflection from the far end is polarized identically with the originalpulse and adds to the pulse rather than cancelling it out. Thus, after around-trip delay, the voltage at the TDR abruptly jumps to twice theoriginally applied voltage. With this in mind, time domainreflectometers may reveal growing resistance levels on joints andconnectors as they corrode, and increasing insulation leakage as itdegrades and absorbs moisture long before either leads to catastrophicfailures. TDRs may also be used to test relatively long lines, such asthose that are impractical to inspect (e.g., due to distance, location,etc) as they locate faults to within centimeters.

Although a fault in the conductive material 13 may not be detected bythe processor 11 until after the fault occurs, the integrity of the line16 is not jeopardized. For example, the fault is likely to occur in theconductive material 13 before reaching the primary 15. Thus, routinemaintenance upon detection in the conductive material 13 should concludewhen the line 16 is wearing away before a fault actually occurs in theline 16.

The advantages of the line 16 include a relatively lightweight manner inwhich the sacrificial materials may be included with the line. Forexample, many lines are very long, such as those employed by aircraft.In fact, an aircraft may include over 100 miles of line for variousdata, communication, and power needs. When metallic ink is used to coatthese lines, the metallic ink adds very little to the overall weight ofthe line 16 as the metallic ink is on the order of a nanometers inthickness. To further illustrate, a much thicker metal foil (e.g.,greater than 200 micrometers) would likely increase the overall weightof the line 16 much more significantly than the metal ink that isapplied to the line 16. Similarly, the sacrificial material 12 generallyadds very little to the overall weight of line 16. For example, Teflontapes and wraps may be configured to be exceptionally thin and lightweight. Such tapes may be used to protect the conductive material 13 butmay also “wear away” prior to a fault in the primary 15 due to theenvironmental conditions to which the line 16 is exposed. Thesacrificial material 12, therefore, provides a minimum layer ofprotection for the purposes of exposing certain line degradingconditions upon detection of the fault in the conductive material 13.

In another embodiment, the conductive material 13 is made conductivethrough the use of nano particulates, such as disclosed in the '463application. For example, the conductive material 13 may be configuredof carbon nanotubes that are typically lighter than conductive metals.Examples of carbon nanotubes include single walled carbon nanotubes thatare generally shaped in a tube having a diameter of about 1 nanometerand a tube length that is much longer. These nanotubes exhibit similarelectric properties of conductivity and electromagnetic shielding thatare found in their metal counterparts. The carbon nanotubes may beconfigured with a lightweight material, such as spandex in a pre-polymerstate. The material may then be applied to the insulating material 14 ofthe line 16.

While providing a relatively lightweight conductive material, the carbonnanotubes may also be made elastic by configuring the carbon nanotubeswith spandex. For example, the conductive primary 15 and the insulatingmaterial 14 may be configured of similarly elastic materials to make theline 16 more resistant to strain. To illustrate, the conductive primary15 may be configured with a substantially dense population of carbonnanotubes within a spandex fiber by mixing the carbon nanotubes whilethe spandex is in a prepolymer state. The dense population of carbonnanotubes may ensure that at least portions of the carbon nanotubesremain in contact with one another when the elastic conductive primary15 is stretched. With the elastic conductive primary 15 formed, theprimary may be surrounded by an insulating material that is alsoelastic. For example, the conductive primary 15 may be surrounded byspandex such that the conductive primary and the insulating material 14may be extruded to form an elastic wire. Thereafter, the conductivematerial 13 and the sacrificial material 12 may be applied to theelastic wire to monitor the integrity of the elastic line 16 over time.

FIG. 2 is a system 50 that provides for the early detection of coaxialcable faults. In this exemplary embodiment, a coaxial cable 40 has atypical configuration that includes a conductive primary 41, aninsulating/dielectric material 42 surrounding the conductive primary 41,a shielding 43 (e.g., braided metal or nano particulate as described inthe '463 application) surrounding the material 42 further surrounded byan insulating layer 44. Differing from a typical configuration of acoaxial cable, are the conductive and insulating layers 13 and 12,respectively. For example, a coaxial cable 40 may be coated with aconductive material 13 to serve as a precursor for degradation in thecoaxial cable. In this regard, a processor 11 may be coupled to theconductive material 13 to transmit a control signal to the conductivematerial 13 and determine a breach in the sacrificial material 12.

The sacrificial material 12 may be configured of a relatively thin andlight weight material that is susceptible to “wear and tear” fromchafing and/or environmental conditions. The sacrificial material 12may, therefore, degrade over time and expose the conductive material 13.The processor 11, by conducting a control signal to the conductivematerial 13, may detect degradations in the conductive material 13. Forexample, the processor 11 may include a TDR that measures the voltage ofthe control signal and its reflections to determine the conductivity ofthe conductive material 13.

Although the wires and cables shown and described herein are illustratedwith the conductive material 13 completely surrounding the insulation,the invention is not intended to be so limited. For example, theconductive material 13 may be implemented as “strands” of conductivematerial that are configured about the length of a wire/cable. In thisregard, the processor 11 described herein may be used to transmit acontrol signal along each strand of the conductive material. By doingso, the processor 11 may be more apt to identify specific locations atwhich degradation occurs along the length of the wire/cable. In otherwords, when the protective sacrificial material 12 is breached at somepoint along the wire/cable, the breach may affect a single strand ofconductive material 13 while not affecting other strands of theconductive material 13. Thus, by using TDR, the processor 11 mayidentify the breached strand of conductive material 13 as well as thelocation of the breach even though other strands along the wire/cableshow no signs of wear and tear.

Moreover, the processor 11 is generally illustrated being coupled to theconductive material 13 any point along the length of the wire or cable.However, the invention is not intended to be so limited. For example,the processor 11 may be configured, at least in part, as an integratedcircuit that is operable within a connector that is used to couple thewire/cable to another device. In this regard, the processor 11 mayreceive power from a “pin” in the connector and operate as describedherein. Accordingly, the processor 11 may be operable determine faultsin the wired/cable in real time.

To illustrate, a TDR module 61 may be configured with a connector 62 asillustrated in FIG. 3. The TDR module 61 may receive power from one ofthe pins 64 to generate a control signal that is propagated along thelength of the wire/cable 63. More particularly, the TDR module 61 maytransmit a control signal along the conductive material (e.g. theconductive material 13 described above) within the wire/cable 63 todetermine faults within the wire/cable 63. Since the TDR module 61 isconfigured with a connector 62, the TDR module 61 may be operable toconvey information regarding a detected fault (e.g., via the pin 65) toa system in which the connector 62 is attached. Alternatively, the pin65 may be coupled directly to the conductive material 13 so as to couplethe conductive material to an external TDR module.

By having this real time monitoring of faults within the wire/cable 63,the faults may be quickly addressed so as to avoid catastrophic failuresof the wire/cable 63. Moreover, the wire/cable 63 may be continuallymonitored in real time so as to maintain statistics on the wire/cable63. For example, the processor 11 may be operable within a real-timesystem, such as an aircraft, that monitors a number of events. Since theprocessor 11 is operable to detect fault conditions within thewire/cable 63 in real time, the processor 11 may correspond certainevents (e.g., storms, lightning, mechanical fault, etc.) with the faultconditions within the wire/cable 63 two further diagnose the faults inthe wire/cable 63.

FIG. 4 is a flowchart of a process 70 for detecting line faults. In thisembodiment, the process 70 initiates when an insulating conductor (e.g.,a coaxial cable, data cable, power cable, or the like) is provided inthe process element 71. The insulating conductor includes conductive andsacrificial layers external to the primary conductor of the wire/cable.These layers may serve as precursors to faults in the insulatingconductor. For example, the conductive layer may be coupled to aprocessor to detect when the sacrificial layer has worn away and exposedthe underlying conductive layer as with the conductive and sacrificialmaterials 13 and 12, respectively above. This wear and tear of thesacrificial layer may further expose the conductive layer toconductivity faults. In this regard, the processor may transmit acontrol signal through the conductive layer in the process element 72.For example, the processor may include a TDR module is used to transmita pulse along the length of the insulated conductor via the conductivelayer. The TDR module may then receive reflection of the transmittedcontrol signal in the process element 73 and measure an electricalcharacteristic of the reflected signal in the process element 74. Thismeasurement may include measuring the voltage of the reflected signal todetermine whether the conductive layer is broken (i.e., open) or evenshorted to an adjacent conductive material (e.g., another worn awaywire/cable, a metal object, or the like).

If the fault is detected in the process element 75, an indication may bemade that the insulated conductor requires repair and/or replacement inthe process element 77. For example, the processor may detect a shortcircuit condition or an open condition that makes the insulatingconductor unsafe and/or inoperable. The processor may then generate acontrol signal that is used to indicate the condition to maintenancepersonnel such that the maintenance personnel may replace or repair theinsulated conductor. Such may be performed in real time and thegenerated data regarding the fault stored until repairs are made.

If no fault is detected in the insulated conductor, the processor mayreturn the insulated conductor to an operable status. In other words,the processor may generate control information that is used to indicateto the maintenance personnel that the insulated conductor is presentlyoperable and not in need of repair/replacement. Since the processor iscapable of performing such fault detection in real-time, the processormay continuously loop through the process 70 by returning to the processelement 72 to determine either intermittent or catastrophic faultswithin the insulated conductor.

In one embodiment, the insulated conductors described herein areconfigured to be elastic as described in the cross referencedprovisional patent application and in the '463 application. Elasticelectrical conductors may have a variety of advantageous uses. Forexample, flexible elastic wires can improve, among other things, wireand cable reliability, body worn comfort, and weight reduction. Flexibleelastic wires may make the wires less susceptible to breakage and/orfaults associated with intermittent conductivity. Moreover, therelatively light weight of the elastomeric fibers may reduce energyassociated with transporting such cables. For example, lighter cables inthe airline industry directly reduce the overall weight of an aircraftthereby reducing the expense of transporting heavier cables. The lighterweight and flexibility of the cables also provides a more effectivemeans for wearable electronics. For example, as more electronics areintegrated with clothing (e.g., a soldier's uniform), lighter weightsare required so that the person may be capable of relativelyunrestricted movement.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and description isto be considered as exemplary and not restrictive in character. Forexample, certain embodiments described hereinabove may be combinablewith other described embodiments and/or arranged in other ways (e.g.,process elements may be performed in other sequences). Accordingly, itshould be understood that only the preferred embodiment and variantsthereof have been shown and described and that all changes andmodifications that come within the spirit of the invention are desiredto be protected.

What is claimed is:
 1. A cable, including: an electrically conductivewire primary; an insulator configured about the electrically conductivewire primary to electrically insulate the electrically conductive wireprimary; an electrically conductive nanoparticulate material configuredabout the insulator and operable to couple to a time domainreflectometer to conduct a time domain reflectometry signal from thetime domain reflectometer along a length of the cable to determine cableintegrity based on voltage changes in the time domain reflectometrysignal; and a sacrificial material configured about the electricallyconductive nanoparticulate material and operable to protect theelectrically conductive nanoparticulate material from wear.
 2. The cableof claim 1, wherein the sacrificial material includesPolytetrafluoroethylene.
 3. The cable of claim 1, wherein thesacrificial material includes polyimide material.
 4. The cable of claim1, wherein the electrically conductive nanoparticulate material includesmetallic ink.
 5. The cable of claim 1, wherein the electricallyconductive nanoparticulate material includes carbon nanotubes.
 6. Thecable of claim 1, wherein the electrically conductive nanoparticulatematerial has a thickness less than about 100 nanometers.
 7. The cable ofclaim 1, wherein the cable is a Universal Serial Bus cable.
 8. A coaxialcable, including an electrically conductive primary; a dielectricmaterial configured about the electrically conductive primary; anelectrical insulator configured about the dielectric material; anelectrically conductive nanoparticulate material configured about theelectrical insulator and operable to couple to a time domainreflectometer to conduct a time domain reflectometry signal from thetime domain reflectometer along a length of the coaxial cable todetermine cable integrity based on voltage changes in the time domainreflectometry signal; and a sacrificial material configured about theelectrically conductive nanoparticulate material and operable to protectthe electrically conductive nanoparticulate material from wear.
 9. Thecoaxial cable of claim 8, wherein the sacrificial material includesPolytetrafluoroethylene.
 10. The coaxial cable of claim 8, wherein thesacrificial material includes polyimide material.
 11. The coaxial cableof claim 8, wherein the electrically conductive nanoparticulate materialincludes metallic ink.
 12. The coaxial cable of claim 8, wherein theelectrically conductive nanoparticulate material includes carbonnanotubes.
 13. The coaxial cable of claim 8, wherein the electricallyconductive nanoparticulate material has a thickness less than about 100nanometers.
 14. An elastic cable, including: an elastic primaryconfigured from an elastic material and embedded with carbon nanotubesthat are operable to conduct electric current through the primary; andan elastic insulator configured about the elastic primary and operableto electrically insulate the elastic primary, wherein the elasticinsulator has an elasticity comparable to the elastic primary, therebyproviding the elastic cable with an elasticity of the elastic primaryand substantially maintaining conductivity of the elastic primary whenstretched.
 15. The elastic cable of claim 14, further including: anelastic shielding configured about the elastic insulator, wherein theelastic shielding includes an electrically conductive material; and anelastic insulator configured about the elastic shielding, wherein theelastic shielding and the elastic insulator about the elastic shieldingconfigure the elastic cable as an elastic coaxial cable.
 16. The elasticcable of claim 15, wherein the electrically conductive material includeswoven metal threads.
 17. The elastic cable of claim 15, wherein theelectrically conductive material includes metallic ink.
 18. The elasticcable of claim 15, wherein the electrically conductive material includesconductive carbon nanotubes.
 19. The elastic cable of claim 14, furtherincluding: an electrically conductive nanoparticulate materialconfigured about the elastic insulator and operable to couple to a timedomain reflectometer and conduct a time domain reflectometry signal fromthe time domain reflectometer along a length of the elastic cable todetermine cable integrity based on voltage changes in the time domainreflectometry signal; and a sacrificial material configured about theelectrically conductive nanoparticulate material and operable to protectthe conductive nanoparticulate material from wear.
 20. The elastic cableof claim 19, wherein the electrically conductive nanoparticulatematerial includes metallic ink.
 21. The elastic cable of claim 19,wherein the electrically conductive nanoparticulate material includescarbon nanotubes.
 22. The elastic cable of claim 19, wherein theelectrically conductive nanoparticulate material has a thickness lessthan about 100 nanometers.
 23. The elastic cable of claim 14, whereinthe elastic cable is an elastic Universal Serial Bus cable.